The purpose of this epidemiologic study is to measure the prevalence of hearing loss and evaluate the relationships of hearing loss and functional changes in the peripheral auditory system to age in a population-based study of middle and older-aged adults. The large (n=4,363) cohort of adults, 48-89 years of age living in Beaver Dam, Wisconsin, will be examined using standardized protocols. Hearing sensitivity, speech recognition, middle-ear function and hair-cell integrity will be measured. A standardized questionnaire about ototoxic drug exposures, noise exposure (adapted from previous epidemiologic studies) and the functional impact of hearing impairment will be administered. This population is already participating in the Beaver Dam Eye Study, an incidence study of age-related ocular disorders. We will use data collected concurrently as part of the eye study, and previously collected data from examinations five years ago, to assess the relationships of diabetes, hypertension, cardiovascular disease and its risk factors (total cholesterol, HDL, smoking, blood pressure, and dietary intake of saturated fat and cholesterol) to age-related decreased hearing sensitivity. We will also measure the 2.5 year incidence and progression of hearing loss in persons over 75 years of age and examine risk factors for progression. Prevalence data from this study will be used for estimating the need for medical counseling and rehabilitative services and projecting health care costs. These data are important because of the large numbers of older persons affected. Such epidemiologic data are necessary to describe persons at increased risk and to allow better understanding of possible etiologic relationships.